Subterranean cavern pump arrangement



1967 P. F. DOUGHERTY ETAL 3,300,983

SUBTERRANEAN CAVERN PUMP ARRANGEMENT Filed March 2, 1964 NON- REVERSE COUPLING PRODUCT V P lN PRODUCT V v OUT DISCHARGE INVENTORS PATRlCK F. DOUGHERTY BY GEORGE M. CLOSS x M jaw ATTORNEY United States Patent f 3,300,983 SUBTERRANEAN CAVERN PUMP ARRANGEMENT Patrick F. Dougherty, Chester Heights, and George M.

Closs, Bryn Mawr, Pa., assignors to Sun 0i] Company,

Philadelphia, Pa., a corporation of New Jersey Fiied Mar. 2, 1964, Ser. No. 348,742 7 Claims. (Cl. 6ll.5)

This invention relates to a pumping arrangement, useful in connection with the storage of fluids under pressure in a subterranean cavern.

Subterranean caverns for fluid storage, which may be mined in rock (granite) for example, are constructed by employing for excavation a large-diameter verticallyextending main or working shaft, through which men, materials, and equipment may be lowered to the cavern area itself, and through which the rock cuttings may be raised to the surface. By way of example, such a shaft may be about forty-two inches in diameter, and the roof of the cavern (at the lower end of the aforesaid shaft) may be on the order of several hundred feet below the surface. To keep this main shaft open, a casing, of fortytwo inches ID. for example, is cemented therein, in much the same way as the casing is cemented in an oil well. This casing is left in the shaft when the cavern is completed, and is used for various purposes (e.g. cavern inspection or maintenance) during the operation of the cavern. This main shaft is essential for the mining of the cavern. For large caverns, this main shaft is (during operation of the cavern for storage purposes) used to conduct the cavern fill pipe (inlet line) to the cavern, as described in our joint Patent No. 3,089,309, dated May 14, 1963.

For large caverns, at least one smaller shaft is drilled to provide good ventilation while the cavern is being mined. Typically, two such smaller shafts are utilized. These smaller shafts are (during operation of the cavern for storage purposes) used for the cavern discharge line (outlet line), as described in Dougherty Patent No. 3,084,515, dated Apr. 9, 1963.

For subterranean caverns of relatively small size, no extra ventilation shaft is needed, suitable ventilation being provided by the main or working shaft. If this single shaft can be used, during operation of the cavern for storage, for both product inlet and product outlet, the cost of constructing the cavern can be considerably reduced.

An object of this invention is to provide a subterranean cavern pumping arrangement by means of which a single shaft in the earth may be used for both product inlet and stored product outlet.

Another object is to provide a subterranean cavern pumping arrangement which utilizes a single pipe (having at the lower end thereof a downhole pump, for product removal or discharge) for both cavern inlet and outlet, without any adverse effect on the downhole pump due to fluid flowing through it in the reverse direction.

The objects of this invention are accomplished, briefly, in the following manner: A single pipe, which is located in a cased shaft, serves as both the fluid inlet and fluid outlet line for a subterranean storage cavern. The bottom of this pipe carries a pump, which is positioned in a sump at the bottom of the cavern and which serves as a discharge pump, for pumping fluid out of the cavern. This pipe, within which is mounted a shaft for operating the aforesaid pump, passes through a safety-type closure. This pipe also serves as the fluid inlet line, for conveying fluid into the cavern for storage. This latter fluid passes down through the pipe and through the pump at the bottom thereof, tending to rotate the latter in the reverse direction. A motor, whose purpose is to rotate the pre- 3,300,983 Patented Jan. 31, 1967 viously-described shaft, is coupled to the upper end of the said shaft through a coupling of non-reverse type.

A detailed description of the invention follows, taken in conjunction with the accompanying drawing, wherein the single figure is a representation, partly schematic, of a subterranean cavern pumping arrangement according to the invention.

Referring now to the drawing, a subterranean mined cavern 1 (mined, e.g., in a rock formation such as granite) can serve as a storage container for a fluid product (such as propane, butane, etc.) 2 under pressure.

Cavern 1 is small, of such a size that only a single shaft 3 is needed for excavating the cavern, this shaft serving for ventilation during mining of the cavern and also serving for the lowering of men, materials, and equipment to the cavern area itself. The single (working) shaft or bore 3 is of rather large diameter, about fortytwo inches for example. A casing 4 (of forty-two inches I.D., for example) is cemented at 5 into the shaft 3, and this casing extends from the surface 6 down to a point a substantial distance below the roof of cavern 1, as will be described in more detail hereinafter. Casing 4 is cemented all the way from the surface 6 down to the cavern roof.

The bottom or base cylindrical shell or skirt 7 of a pressure vessel 8 is butt-welded onto the top of easing 4, at a oint about thirteen feet below grade 6. This pressure vessel is a prefabricated vessel which has been suitably stress-relieved, and includes a bottom dished head or closure 9, and an upper removable head or closure 10 (which is illustrated, for simplicity, as also being dished). The vessel 8 is substantially cylindrical with an ID. of forty-two inches. The bottom closure 9 is permanently sealed to vessel 8 adjacent the skirt 7; also, the vessel 8 is welded in lengthwise position onto the top of the casing 4. The closure 9 is located a distance of ten feet, more or less, below 'grade 6, and provides a closure which in effect seals off the casing 4 (and the cavern 1) from the interior of pressure vessel 8 and also, of course, from the atmosphere above the surface 6. Preferably, a manway (not shown) as sealed through the bottom closure 9, for access to the cavern when desired; a typical manway construction is shown in the 309 patent previously referred to.

As previously stated, the bottom closure 9 is sealed to vessel 8 and is located below the surface of the earth. The upper closure 10 is also normally sealed to vessel 8, and is located above the surface of the earth. For further details regarding the construction of vessel 8 and closures 9 and 10, reference may be had to the aforementioned 309 patent; since such details form no part of the present invention, they will not be referred to further herein. As described in detail in the 309 patent, the arrangement 8-10 comprises a safety-type closure.

A sump 11 is provided in the floor 12 of cavern 1, this sump being located vertically below bore 3 and concentric therewith. By way of example, sump 11 may be approximately cylindrical in configuration, with a depth of twenty-two feet below the floor of cavern 1 and with a diameter of 7 /2 feet. Casing 4 extends below the roof of the cavern 1, entirely through the vertical dimension of the cavern and down into stunp 11. The lower open end of casing 4 may be flanged inwardly, as at 4a. This lower end 4a may be located about 12 /2 feet below the floor 12. Ondinarily, as described in the 51S patent previously referred to, there will be a layer of water,

(not shown) in sump 11, below the fluid product 2, since water continuously seeps into the cavern 1 and since this water is heavier than the fluid product 2 stored in cavern 1, and is immiscible therewith.

In order to transfer or discharge fluid product from cavern 1 (i.e., to provide a fluid outlet means for the cavern), as well as to occasionally pump out the water which collects in sump 11, a pump 13 is utilized. This pump has its intake (schematically indicated at 14) extending into sump 11, below the lower end 4a of easing 4. By way of example, the lower end of the intake 14 may be located about eight feet above the bottom of sump 11, and about twenty inches below the lower end 4a of casing 4. The pump 13, which is diagrammatically illustrated, may be of the deep-well, submersible, multistage turbine type; I

Pump 13 is secured to the lower end of a pipe 15 (eight inches in diameter, for example) which is positioned concentrically within casing 4. The discharge connection of pump 13 (schematically indicated at 16) is coupled to the lower end of pipe 15, so that this pump, when operating, discharges the fluid pumped thereby into the interior of pipe 15. Pump 13 abstracts fluid from sump 11 by way of pump intake 14, and discharges it, by way of pump discharge 16, into the lower end of pipe 15, and it then travels to the surface through this latter pipe.-

Pipe 15 extends upwardly from pump 13, concentrically of easing 4, and is sealed through the bottom closure 9 and the upper closure provided by vessel 8. By means of this construction, the upper end of pipe is in effect fastened to the upper end of casing 4, Since pipe 15 is thus fastened only at its upper end to the casing, pipe 15 with its appendant pump 13 hangs freely in the easing 4,-

, Above upper closure 10, a side pipe coupling 17 (shown for simplicity as merely forming a T with the upper end of pipe 15), having the same diameter as pipe 15, is sealed through the cylindrical wall of pipe 15 and is suitably joined to a pipe which extends to a T fitting 18. From the T 18, a discharge pipe 13 leads through a valve 20 to a product out line 21. Thus, discharge or fluid transfer pump 13 can, when suitably mechanically driven, pump fluid from the cavern sump 11 through a fluid outlet path comprising pipe 15 (in which the fluid then travels upwardly), coupling 17, fitting 18, pipe 19, valve 20, and line 21. When discharge from the cavern takes place, valve 24 is closed.

In order to drive the pump 13 from the surface, a rotatable pump drive shaft 22 is utilized. This shaft is mounted and supported for rotation in pipe 15, concentrically thereof, and extends from a point above the surface 6 down to the pump 13. Shaft 22 is driven by a motor at the surface, in a manner to be described hereinafter, and in turn mechanically drives the pump 13 at the bottom of pipe 15. Shaft 22 is supported and journaled within pipe 15 in a manner conventional in deepwell pump practice; a typical arrangement of this pipe is described in the aforementioned 515 patent.

Above coupling 17, a suitable closure member (not shown (is provided for seating oif the upper end of pipe 15 from the atmosphere. A mechanical seal arrangement is utilized to seal the rotatable pump shaft 22 through this closure, whereby to complete the seal at the upper end of pipe 15. The closure and mechanical seal arrangement just referred to are rather conventional and may be, for example, of the type described in the previously-mentioned 515 patent.

The pipe 15 is also used for filling the cavern (i.e., it is used as a stored fluid inlet), in addition to its previously-described function of providing a stored fluid outlet or discharge. From the fitting 18, a fill line or fill pipe 23 is coupled through a valve 24 to the discharge of a cavern fill pump 25, to the intake of which pump is coupled a product in line 26. When it is desired to add fluid to cavern 1, valve 24 is opened (valve 20 being closed at this time), pump 25 is energized, and the fluid is pumped, under superatmospheric pressure, from line 26 through a fluid inlet path comprising valve 24, pipe 23, fitting 18, coupling 17, pipe 15 (in which the. fluid then travels downwardly), pump 13 (through .4 which the fluid then travels downwardly or in the reverse direction, as compared to the normal pumping direction of this pump), and cavern sump 11.

In order to prevent damage to the pump 13, it is essential that this pump be automatically prevented from turning backward when fluid is being pumped downwardly through the pipe 15 (and downwardly through pump 13) into the cavern, that is, when the cavern 1 is being filled. This function is performed by means of a non-reverse coupling, in a manner which will be described hereinafter. Providing this protective function is accomplished, the single pipe 15 (in the single shaft 3, the only shaft used for constructing the cavern 1) can be used as both fluid inlet (cavern filling) and fluid outlet (cavern discharge).

An electric motor 27, having a hollow output shaft, is mounted above the mechanical seal and closure which are above coupling 17; this motor provides the motive power for rotating the pump drive shaft 22 and thus for driving pump 13. Pump shaft 22 is positioned within the hollow motor shaft, and extends therethrough up to the top of the motor 27, where a non-reverse coupling 28 is used to couple the motor output shaft to the pump drive shaft 22.

The non-reverse coupling 28 is of the type commonly used in connection with vertical electric motors which drive deep-well turbine pumps. It is a mechanical device which prevents backward rotation of the motor, and thus also of the pump shaft 22 (and, of course, the pump 13) which is coupled to the motor shaft. It consists essentially of a ratchet plate bolted securely to the motor frame, and spring-pressed pins which are adapted to engage this plate and which are carried by a pin carrier which is in turn secured to the bolted-together coupling between the motor output shaft and the pump shaft 22. When the motor 27 starts in the normal (forward) direction, the pins move upward after a few revolutions and are held upward by centrifugal force, so as to clear the stationary teeth of the ratchet plate. (Due to the non-symmetrical design of the ratchet plate teeth, the pins are free to start rotating in this direction.) However, when the pump shaft 22 tries to turn backward (as a result of fluid traveling in the reverse direction through pump 13, when the cavity is being filled), the pins engage the teeth of the ratchet plate and lock therein, thus preventing rotation of the pump shaft 22, and of the pump 13, in this direction. Such non-reverse couplings are well-known in the deep-well pump art, so a more detailed description thereof is believed unnecessary.

The invention claimed is:

1. In a subterranean cavern for storing a fluid at superatmospheric pressure: a fluid transfer pipe extending from the surface of the earth downwardly to the bottom of said cavern, a fluid transfer pump mounted at the lower end of said pipe for pumping fluid from said cavern upwardly through said pipe to the surface, said pump having its intake at the lower end of said pipe; pump means coupled to said pipe for producing a pressured flow of fluid downwardly through said ipe from the surface and downwardly through said pump into said cavern for storage therein, and means coupled to said pump for preventing rotation thereof as a result of fluid flowing downwardly therethrough.

2. An arrangement as defined in claim 1, including also a motor located at the surface for driving said transfer pump; said last-named means comprising a coupling of non-reverse type between said motor and said transfer pump.

3. An arrangement as described in claim 1, wherein said cavern has a sump extending downwardly from the floor thereof and communicating therewith, and wherein the intake for said transfer pump is located in said sump; said arrangement including also a motor located at the surface for driving said transfer pump; said last-named means comprising a coupling of non-reverse type between said motor and said transfer pump.

4. In a subterranean cavern for storing a fluid at superatmospheric pressure: a fluid transfer pipe extending from the surface of the earth downwardly to the bottom of said cavern, a fluid transfer pump mounted at the lower end of said pipe for pumping fluid from said cavern upwardly through said pipe to the surface, said pump having its intake at the lower end of said pipe; a rotatable drive shaft passing downwardly through said pipe from the surface to said pump and coupled to said pump for efiecting rotation of the latter in one direction, pump means coupled to said pipe for producing a pressured flow of fluid downwardly through said pipe from the surface and downwardly through said pump into said cavern for storage therein, and means coupled to said drive shaft for preventing rotation thereof, and of said pump, in the other direction.

5. An arrangement as defined in claim 4, including also a motor located at the surface for driving said transfer pump; said last-named means comprising a coupling of non-reverse type between said motor and the upper end of said drive shaft.

6. An arrangement as described in claim 4, wherein said cavern has a sump extending downwardly from the floor thereof and communicating therewith, and wherein the intake for said transfer pump is located in said sump; said arrangement including also a motor located at the surface for driving said transfer pump; said last-named means comprising a coupling of non-reverse type between said motor and the upper end of said drive shaft.

7. In a subterranean cavern for storing a fluid at superatmospheric pressure, said cavern having a single communicating shaft extending from the surface of the earth downwardly to the cavern: a casing sealed in said shaft, a closure sealed into said casing below the surface of the earth, another closure sealed to the upper end of said casing, above the surface of the earth, a fluid transfer pipe located in said shaft, sealed through both closures, and extending downwardly to the bottom of said cavern; a fluid transfer pump mounted at the lower end of said pipe for pumping fluid from said cavern upwardly through said pipe to the surface, said pump having its intake at the lower end of said pipe; a rotatable drive shaft passing downwardly through said pipe from the surface to said pump and coupled to said pump for effecting rotation of the latter in the forward direction, pump means coupled to said pipe for producing a pressured flow of fluid downwardly through said pipe from the surface and downwardly through said pump into said cavern for storage therein, a motor located at the surface for driving said pump, and a coupling of non-reverse type between said motor and the upper end of said drive shaft.

References Cited by the Examiner UNITED STATES PATENTS 1,499,923 7/1924 Hall.

1,516,681 11/1924 Palmer 103111 2,580,332 12/1951 Teetor 166106 X 2,880,593 4/1959 Johnson et al 61-.5 X 2,884,761 5/1959 Miles at al. 61-.5 3,084,515 4/1963 Dougherty 61-.5

EARL J. WITMER, Primary Examiner. 

1. IN A SUBTERRANEAN CAVERN FOR STORING A FLUID AT SUPERATMOSPHERIC PRESSURE: A FLUID TRANSFER PIPE EXTENDING FROM THE SURFACE OF THE EARTH DOWNWARDLY TO THE BOTTOM OF SAID CAVERN, A FLUID TRANSFER PUMP MOUNTED AT THE LOWER END OF SAID PIPE FOR PUMPING FLUID FROM SAID CAVERN UPWARDLY THROUGH SAID PIPE TO THE SURFACE, SAID PUMP HAVING ITS INTAKE AT THE LOWER END OF SAID PIPE; PUMP MEANS COUPLED TO SAID PIPE FOR PRODUCING A PRESSURED FLOW OF FLUID DOWNWARDLY THROUGH SAID PIPE FROM THE SURFACE AND DOWNWARDLY THROUGH SAID PUMP INTO SAID CAVERN FOR 